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At least 109 records · Page 6Linked to original sources
PubMed2005

Hybrid disadvantage in the larval foraging behaviour of the two neotropical species of Drosophila pavani and Drosophila gaucha.

Flies from two populations of the Chilean endemic neotropical species Drosophila pavani and two populations of its sibling species Drosophila gaucha were crossed reciprocally to obtain intra- and interspecific hybrids. The developmental pathways of locomotor activity and feeding rate were analysed for eleven of twelve possible genotype groups. The hybrids showed reduced fitness indicated by a decrease in the measured traits. Hybrid disadvantage was strongest in interspecific hybrids, especially with respect to feeding behaviour. This evidence supports the contention that D. pavani and D. gaucha have evolved different coadapted gene pools controlling the developmental pathways for behavioural traits expressed during larval foraging; but genetic divergence affecting these behaviours has also taken place between locally adapted populations within each species.

Animals↗
PubMedDate not supplied

Karyotypic relationships among the tribes of Hypostominae (Siluriformes: Loricariidae) with description of XO sex chromosome system in a Neotropical fish species.

The family Loricariidae, with about 683 species, is one the largest fish families in the world. The subfamily Hypostominae was recently reviewed and is now divided in five tribes. With the main objective of contributing to a better understanding of the relationships of the members of the subfamily Hypostominae, cytogenetic analyses were conducted in seven species (three Hypostomini, three Pterygoplichthini and two Ancistrini) from Brazil and Venezuela. In Pterygoplichthini, all species show 2n = 52 chromosomes. In Hypostomini Hypostomus ancistroides has 2n = 68, H. regani 2n = 72 and Hypostomus goyazensis 2n = 72 chromosomes. In Ancistrini Ancistrus n. sp. 1 has 2n = 39/40 with a sex chromosome system of the type XX/X0, which is a novelty for neotropical fishes, and Ancistrus n. sp. 2 has 2n = 52 chromosomes. Six species have single Ag-NORs and two multiple Ag-NORs. The possible cytogenetic relationships among the species of Hypostominae are discussed.

Animals↗
PubMed2005

Kinetics of the natural evolution of hydrogen cyanide in plants in neotropical Pteridium arachnoideum and its ecological significance.

The time-dependent natural release of hydrogen cyanide (HCN) was studied quantitatively using young croziers of the neotropical bracken fern Pteridium arachnoideum. HCN production was quantified in crushed tissue using a flow reactor at 30.0 +/- 0.1 degrees C. Released HCN was carried into appropriate traps with a moist air flow. Aliquots were drawn from the traps at fixed time intervals, and the HCN concentration was evaluated spectroscopically. All available prunasin (Pru), the only cyanogenic glycoside present, underwent decomposition into HCN in less than 1200 min. Fiddleheads (N = 76) contained 1.84-107.70 mg Pru g(1) dw in a continuous fashion suggesting genetic polymorphism. Acyanogenic morphs were rare (1/77). From the kinetics of the samples with Pru content near the median histographic distribution (N = 46), accumulated HCN formation as a function of time, initial velocities, average HCN production rate, and corresponding rate equations were obtained. Initial and average velocities correlated well with total Pru content. The yield of cyanide liberation varied widely between 0.51 and 47.86 microg HCN min(-1) g(-1) dw and was a linear function of [Pru]t. However, the beta-glucosidase enzyme involved in this reaction was not rate limiting and occurs in excess in the natural system. Enzyme activity was found to be independent of [Pru]t. The contribution of HCN as an allomone-upon-request against herbivores was assessed quantitatively. Bracken fiddleheads produced a pulse of HCN soon after tissue injury that waned rapidly, leaving a large portion of intact prunasin to decompose more slowly in the herbivore's lumen. The balance between the external and internal courses was found to depend on the concentration of prunasin in the plant, the amount of crozier eaten, and the time used to consume it.

Biological Evolution↗
PubMed1990

Temperature effects on metabolism, ventilation, and oxygen extraction in a Neotropical bat.

We examined the relationship between ambient temperature (Ta), body temperature (Tb), oxygen consumption (VO2), carbon dioxide production (VCO2), evaporative water loss (mH2O), respiratory frequency (f), tidal volume (VT), minute volume (VI), and oxygen extraction (EO2) in the Neotropical bat Noctilio albiventris (mean mass 40 g). The factorial aerobic scope was 7.2 between Ta of 1-35 degrees C (VO2 = 0.119 and 0.0165 ml/(g.min), respectively). The respiratory exchange ratio (VCO2/VO2) did not change with Ta and mH2O was constant between Ta of 10-35 degrees C. Thermal conductance was minimal at 30 degrees C and constant and low at Ta less than 30 degrees C. Between 10 and 35 degrees C, Noctilio accommodated changing VO2 with parallel and roughly equivalent changes in f, VT, and EO2. The change in VO2 between 10 and 1 degrees C was accommodated mainly through changing f. Ventilation parameters in resting thermoneutral Noctilio are intermediate between allometric values for birds and mammals. Maximal EO2 in Noctilio (35-40%) is higher than for other mammals but considerably less than maximal EO2 in some birds.

Animals↗
PubMed1983

Experimental parasitization of eggs of Triatoma maculata (Erichson) by the oriental microhymenopteran, Gryon triatomae Masner and comment on the susceptibility of other neotropical triatomines.

The oriental microhymenopteran wasp, Gryon triatomae Masner, 1975 was reared in eggs of triatomine bugs, including vectors of Chagas' disease. In particular, G. triatomae was maintained for 31 generations in eggs of Triatoma maculata (Erichson). Only one parasite develops in each bug egg and 30 to 40 days are required for completion of development at 24 +/- 1 degrees C. Mean parasitization rate of 7484 eggs of T. maculata, in 54 rearings, was 34.7% with a range from zero to the highest rate of 86.7%. Mated females produce predominantly female progeny (mean sex ratio, 1 male:6.7 females). Unmated females produce parthenogenetic males. The wasp reproduces in fertile eggs, from those recently laid to those with well-advanced bug embryos. Infertile eggs are not usually parasitized. Both sexes survive for one to two weeks unfed, but for several weeks (up to 16 for females) if fed (on honey). Frequent ovipositions may reduce survival. Successful parasitization by females persisted for about three weeks but declined subsequently. Abortions of developing Gryon were usually 10% or less. Brief comparison with other neotropical triatomine species indicates that eggs of Triatoma spp. are susceptible to G. triatomae; Panstrongylus spp. seem relatively poor hosts, and there is little or no parasitization of Rhodnius spp.

Animals↗
PubMed1984

A case of envenomation by the neotropical colubrid snake, Stenorrhina freminvillei.

The case history of a bite by the neotropical opisthoglyph, Stenorrhina freminvillei, is presented. This is apparently the first documentation of human envenomation by this genus. Localized pain and swelling were the predominant symptoms; no systemic reaction was noted. Such mild effects are consistent with the bites reported for other New World colubrids, in contrast to the potentially lethal effects produced by Old World colubrid genera Dispholidus, Thelotornis, Rhabdophis and Atractaspis.

Animals↗
PubMed1987

Further classification of skin alkaloids from neotropical poison frogs (Dendrobatidae), with a general survey of toxic/noxious substances in the amphibia.

Cutaneous granular glands are a shared character of adult amphibians, including caecilians, and are thought to be the source of most biologically active compounds in amphibian skin. Data are available from one or more species in over 100 of nearly 400 genera comprising the three living orders of Amphibia. Many species contain unidentified substances judged to be noxious based on predator aversion or human taste. Additionally, there is a great diversity of known compounds, some highly toxic as well as noxious, which can be tabulated under four broad categories: biogenic amines, peptides, bufodienolides (bufogenins) and alkaloids. The last category includes alkaloids derived from biogenic amines, water-soluble alkaloids (tetrodotoxins) and lipophilic alkaloids. Most compounds are known only from skin of adult amphibians, but the toxic and noxious properties of eggs and larvae of certain salamanders and toads can be attributed to tetrodotoxins and bufodienolides, which occur also in adult tissues other than skin. Predator aversion and various antipredator behaviors and aposematic colorations clearly prove the defensive value of these diverse metabolites, whether or not they are elaborated primarily (e.g. alkaloids) or secondarily (e.g. some peptides and biogenic amines) for this function. Lipophilic alkaloids include the samandarine alkaloids, known definitely only from an Old World genus of salamanders, and the more than 200 dendrobatid alkaloids. Nearly all the latter are unique to neotropical poison frogs of the genera Dendrobates and Phyllobates (Dendrobatidae), except for seemingly homoplastic occurrences of a few such alkaloids in small brightly colored anurans of several other families. Owing to recent discoveries and new structural information, the dendrobatid alkaloids are here partitioned among the following major and minor classes: batrachotoxins, histrionicotoxins, indolizidines, pumiliotoxin-A class and its allopumiliotoxin and homopumiliotoxin subclasses, decahydroquinolines, gephyrotoxins, 2,6-disubstituted piperidines, 2,5-disubstituted pyrrolidines, pyridyl-piperidines, indole alkaloids, azatricyclododecenes and amidine alkaloids. Except for the steroidal batrachotoxins, and the minor classes of pyrrolidine alkaloids, indole alkaloids and amidine alkaloids, all the above contain a piperidine ring. A large number of piperidine-based alkaloids occur mainly as trace compounds in Dendrobates and remain unclassified; the only water-soluble toxin so far discovered in a dendrobatid (Colostethus) is structurally unknown, but conceivably an alkaloid.

Alkaloids↗
PubMed1995

Metabolic rates and thermal conductance in four species of neotropical bats roosting in hot caves.

Data are presented on metabolic rates and thermal conductance for four species of neotropical bats, Pteronotus quadridens, Mormoops blainvillii (Mormoopidae), Monophyllus redmani and Erophylla bombifrons (Phyllostomidae). Each of these bats predominantly or exclusively roosts in hot caves (28-40 degrees C) in Puerto Rico. Basal metabolic rates (BMR) for these four species were 55%, 48%, 66%, and 66% of values expected from the Kleiber curve, respectively. Thermal conductance was 93%, 55%, 175%, and 158% of values expected from the Aschoff curve, respectively. These data indicate that, in addition to food habits, variation in BMR is highly correlated to roost microclimate. Pteronotus and Mormoops, like other insectivorous species, have low BMRs. The low BMR of the nectar/fruit eating Monophyllus and Erophylla, as well as the low termal conductance in Mormoops, is consistent with their habit of roosting in hot caves, suggesting that roost microclimate is an important selective force in the physiological adaptation of these bats.

Adaptation, Physiological↗
PubMed2005

A novel butyrylcholinesterase from serum of Leporinus macrocephalus, a Neotropical fish.

We show here that serum of piaussu, a Neotropical characin fish, has the highest butyrylcholinesterase activity so far described for humans and fish. To clarify whether this cholinesterase could protect piaussu against anticholinesterase pesticides by scavenging organophosphates, we purified it 1700-fold, with a yield of 80%. Augmenting concentrations (from 0.01 to 20 mM) of butyrylthiocholine activated it. The pure enzyme was highly inhibited by chlorpyriphos-oxon (ki=10,434x10(6) M-1 min-1) and by the specific butyrylcholinesterase inhibitor, isoOMPA (ki=45.7x10(6) M-1 min-1). Electrophoresis of total serum and 2-D electrophoresis of the purified cholinesterase showed that some enzyme molecules could circulate in piaussu serum as heterogeneously glycosylated dimers. The enzyme's N-terminal sequence was similar to sequences found for butyrylcholinesterase from sera of other vertebrates. Altogether, our data present a novel butyrylcholinesterase with the potential of protecting a fish from poisoning by organophosphates.

Amino Acid Sequence↗
PubMed2006

Cardiac function of two ecologically distinct Neotropical freshwater fish: Curimbata, Prochilodus lineatus (Teleostei, Prochilodontidae), and trahira, Hoplias malabaricus (Teleostei, Erythrinidae).

An isometric muscle preparation was used to investigate the importance of the ventricular sarcoplasmic reticulum (SR) and extracellular Ca(2+) (2.5 up to 10.5 mM) to force generation at 25 degrees C (acclimation temperature) in two ecologically distinct Neotropical teleost fish: Curimbata (active species), and trahira (sedentary species). The post-rest force was studied with and without 10 muM ryanodine in the medium. The positive inotropism observed for both species in response to increases on extracellular Ca(2+) reflected a greater Ca(2+) influx through sarcolemma, as well as an increase in Ca(2+) liberation from the SR by the Ca(2+)-induced Ca(2+) release mechanism. The significant post-rest potentiation recorded for the curimbata and trahira control preparations (3.22+/-0.24 to 6.55+/-0.77 mN mm(-2) and 0.74+/-0.07 to 2.26+/-0.26 mN mm(-2), respectively), was completely inhibited by the addition of ryanodine to the bathing medium, suggesting a potential functionality of SR for both species. Considering the differences in these species habitats, modes of life and levels of activity and the fact of a probable SR Ca(2+) cycling in a physiological temperature, we suggest that the functionality of the SR in these species is probably related to their phylogeny.

Animals↗
PubMed2004

Air breathing of the neotropical fishes Lepidosiren paradoxa, Hoplerythrinus unitaeniatus and Hoplosternum littorale during aquatic hypoxia.

The present study investigated the respiratory rates, frequency of air breathing and ability to extract oxygen from air compared to body mass of three neotropical air-breathing fishes (Lepidosiren paradoxa, Hoplerythrinus unitaeniatus and Hoplosternum littorale) with different accessory organs, under the same conditions of hypoxia (PO(2)<5 mm Hg) and temperature (25 degrees C), using the same apparatus. The results indicated a superior capacity of H. littorale (16.01 ml O(2) breath(-1) kg(-1)) compared to H. unitaeniatus (7.03 ml O(2) breath(-1) kg(-1)) and L. paradoxa (4.95 ml O(2) breath(-1) kg(-1)).

Air↗
PubMed2004

Sugar preferences, absorption efficiency and water influx in a Neotropical nectarivorous passerine, the Bananaquit (Coereba flaveola).

Nectarivory has evolved repeatedly in a number of unrelated bird taxa throughout the world and nectar feeding birds, regardless of their taxonomic affiliation, display convergent foraging and food processing adaptations that allow them to subsist on weak sugar solutions. However, phylogeny influences sugar type preferences of nectarivores. We investigated sugar preferences, assimilation efficiency and water flux in a Neotropical honeycreeper, the Bananaquit (Coereba flaveola; Coerebidae), a member of a radiation of tanagers and finches. Bananaquits showed no preference for nearly equicaloric (25% w/v) sucrose, glucose, fructose or glucose-fructose mixtures in pair-wise choice tests. In agreement with this lack of preference, they were equally efficient at absorbing sucrose and both hexoses. Apparent assimilation efficiency of these sugars was around 97.5%. In pair-wise tests, Bananaquits displayed a strong preference for the most concentrated sucrose solution when the lowest concentration ranged from 276 to 522 mM. Between 522 and 1120 mM sucrose solution concentrations, Bananaquits were able to adjust their volumetric food intake in order to maintain a constant energy intake. At solution concentration of 276 mM, birds could not maintain their rate of energy intake by increasing food consumption enough. We consider that at low sugar concentrations, Bananaquits faced a physiological constraint; they were unable to process food at a fast enough rate to meet their energy needs. We also explored the possibility that dilute nectars might be essential to sustain high water needs of Bananaquits by allowing them to control osmolarity of the food. Between 276 and 1120 mM sucrose solution concentrations, average amount of free water drunk by Bananaquits was independent of food concentration. They drank very little supplementary water and did not effectively dilute concentrated nectars. The evidence suggests that water bulk of dilute nectars is a burden to Bananaquits.

Animals↗
PubMed2005

Flow cytometry identification and characterization of mononuclear cell subsets in the neotropical primate Saimiri sciureus (squirrel monkey).

BACKGROUND: The neotropical primate squirrel monkey is used in many areas of biomedical research including neuroendocrinology, immunology and infectious diseases. However, research has been hampered by the lack of immunological tools for this primate. METHODS: A series of 67 commercially available monoclonal antibodies to human CD antigens or cytokines were tested on Saimiri mononuclear cells and the specificity was assessed by double staining using flow cytometry. RESULTS: Monoclonal antibodies defining the main mononuclear cells subsets (monocytes, B, T, including CD4 and CD8 T cells) as well as activation markers have been identified. The conditions to specifically identify the various cell subsets using two color flow cytometry and establish their relative proportions have been set-up. We also have established normal values of the main circulating mononuclear cell subsets for adult Saimiri sciureus monkeys from the breeding unit of Institut Pasteur in French Guiana. The distribution between spleen, blood and lymph nodes has been compared. CONCLUSIONS: These tools allow documenting the phenotype of most Saimiri mononuclear cell subsets and assessing their activation level. This opens new perspectives for vaccinology and immunopathology research in this experimental non-human primate host, in particular for malaria research.

Animals↗
PubMed2004

Mechanical properties of calcified exoskeleton from the neotropical millipede, Nyssodesmus python.

The calcified exoskeleton of millipedes plays a crucial role in resisting large forces developed during burrowing locomotion. I measured morphological and mechanical properties of cuticle from the neotropical forest floor millipede, Nyssodesmus python (Diplopoda: Polydesmidae), which ranges in body mass from 2 to 7 g. Scaling of thickness of the cuticle with respect to body mass followed predictions of geometric similarity. Both fracture strength and Young's modulus increased with body mass in females but not in males. In spite of their smaller size, male millipedes were still stronger, on average, than female millipedes. Mean fracture strength of millipede cuticle was 124 MPa, and Young's modulus was 17 GPa. Both of these values exceed measurements from typical insect cuticle, suggesting that calcium salts may play a role in stiffening and strengthening the millipede exoskeleton. Because of the high density of calcified millipede cuticle (1660 kg/m3), stiffness and strength relative to body weight remain comparable to values for other insect cuticles. These results corroborate a previous hypothesis that absolute not specific strength and stiffness have been selective factors in the evolution of millipede cuticle, and that bulkiness of the exoskeleton has been minimized through the deposition of calcium salts.

Animals↗
PubMed2004

Geographic variation of metric properties within the neotropical sandflies.

Traditional morphometrics remains a useful tool for differentiating sandflies species, particularly closely related taxa. Within a single species, however, size variation among geographic populations might interfere with species distinction. In the past decades, a search for a metric property less prone to individual variations led to the use of ratios, and more recently to the use of size-free variables (after tentative size extraction). While morphometrics is continuously enriched with new, more efficient techniques describing shape, the question remains for the morphologist whether an efficient removing of within-species size variation is sufficient to produce stable, specific characters. Is a single species metrically recognizable in spite of its geographical variation? To address this question the intraspecific variation in 10 neotropical sandflies was examined within and between large South American ecogeographic regions: the Amazonian region, the Sub-Andean and the Chaco regions of Bolivia, and the Atlantic Coast of Brazil. Thus, the geographic stability of metric properties, as derived from measurements between landmarks, was investigated 10 times allowing a total of 29 inter-regional and 13 intra-regional conspecific comparisons. Metric proportions remained stable among conspecific populations of a single ecogeographic region. From one region to another, however, size-independent changes were significant and their amount was correlated with altitude. This could reflect an important role of some environmental changes in shaping the insects, and should be taken into account when using morphometrics to identify sandflies.

Altitude↗
PubMed2004

Structural and biological characterization of two novel peptides from the venom of the neotropical social wasp Agelaia pallipes pallipes.

The venom of the neotropical social wasp Agelaia pallipes pallipes was fractionated by RP-HPLC resulting in the elution of seven fractions; the last two were re-fractionated under RP-HPLC by using isocratic elution conditions and the purity of the fractions were confirmed by using ESI-MS analysis. Both fractions are constituted of peptide components, which were sequenced by Edman degradation chemistry, resulting in the following sequences: Protonectin I-L-G-T-I-L-G-L-L-K-G-L-NH(2). Agelaia-MP I-N-W-L-K-L-G-K-A-I-I-D-A-L-NH(2). Both peptides are manually synthesized on solid-phase and functionally characterized by using Wistar rats cells. Protonectin is a non-hemolytic chemotactic peptide for polymorphonucleated leukocytes (PMNL), presenting some mast cell degranulating activity and potent antimicrobial action both against Gram-positive and Gram-negative bacteria. Agelaia-MP was characterized as a hemolytic mast cell degranulator toxin, presenting a poor antimicrobial action and no chemotaxis for PMNL.

Amino Acid Sequence↗
PubMed2005

Structural and biological characterization of three novel mastoparan peptides from the venom of the neotropical social wasp Protopolybia exigua (Saussure).

The venom of the Neotropical social wasp Protopolybia exigua(Saussure) was fractionated by RP-HPLC resulting in the elution of 20 fractions. The homogeneity of the preparations were checked out by using ESI-MS analysis and the fractions 15, 17 and 19 (eluted at the most hydrophobic conditions) were enough pure to be sequenced by Edman degradation chemistry, resulting in the following sequences: Protopolybia MPI I-N-W-L-K-L-G-K-K-V-S-A-I-L-NH2 Protopolybia-MP II I-N-W-K-A-I-I-E-A-A-K-Q-A-L-NH2 Protopolybia-MP III I-N-W-L-K-L-G-K-A-V-I-D-A-L-NH2 All the peptides were manually synthesized on-solid phase and functionally characterized. Protopolybia-MP I is a hemolytic mastoparan, probably acting on mast cells by assembling in plasma membrane, resulting in pore formation; meanwhile, the peptides Protopolybia-MP II and -MP III were characterized as a non-hemolytic mast cell degranulator toxins, which apparently act by virtue of their binding to G-protein receptor, activating the mast cell degranulation.

Amino Acid Sequence↗
PubMed2004

Methyl-paraoxon comparative inhibition kinetics for acetylcholinesterases from brain of neotropical fishes.

Acetylcholinesterase (AChE) sensitivity to the organophosphorus (OP) pesticide methyl-paraoxon was measured in fourteen species of Neotropical marine and freshwater fish found in the waters of Brazil. The rate constant for phosphorylation, kp, the dissociation constant, kd, the second order rate constant, ki, and the IC50 value were measured at 28 degrees C in pH 7.5 buffer for AChE extracted from brain. In addition, the substrate affinity constant, km, was measured with acetylthiocholine. The IC50 for 30 min of inhibition ranged from 123 nM (Prochilodus lineatus) to 3340 nM (Percophis brasiliensis), which corresponded to ki values of 187-6.9 mM(-1) min(-1). A 10-fold range in kp values from 0.21 min(-1) (Paralonchurus brasiliensis) to 2.1 min(-1) (Dules auriga) was associated with a 37-fold range in kd values from 4 to 150 microM. These large differences in reactivity with methyl-paraoxon were not reflected in the binding affinity for acetylthiocholine; km values were approximately 0.1-0.3 mM for all species. These results predict that the amino acid sequence involved in AChE sensitivity differs in these fishes, and that consequently some fish species may be resistant to the toxicity of methyl-paraoxon.

Acetylcholinesterase↗